Fuel system



. Feb. 7, 1967 J. B. YORK, JR 3,302,935

FUEL SYSTEM Filed Sept. 16, 1965 AIR /7 PUMP TO lNJECTOR NOZZLES INVENTORA c/e/vme 73 Vorfifdlr zxzw ATTORNEY United States Patent of Delaware Filed Sept. 16, 1965, Ser. No. 487,802 4 Claims. (Cl. 26129) This invention relates to fuel systems and more particularly relates to fuel systems utilizing fluid amplifier technology.

Many fuel injection systems in present use include a venturi located in the air inlet to create a pressure signal which varies with the rate of air flow to the engine; this pressure signal determines the rate at which fuel is delivered to the injector nozzles. Unfortunately however, the venturi signal does not vary linearly with air flow. Thus, the area of the venturi opening must be relatively small to create a pressure signal sufficient to meter fuel at low air flow rates. Such a venturi necessarily restricts the air inlet and reduces the maximum air flow which could otherwise be consumed by the engine.

In addition, such systems require separate means to develop a metering signal when the engine is idling and the rate of air flow is very low. This signal is less sensitive to the fuel requirements of the engine, and therefore the systems must be manufactured and calibrated with a high degree of accuracy.

This invention eliminates the necessity for a separate idle system and at the same time allows use of a larger venturi, thus reducing the restriction of air flow to the engine, by providing means to amplify the venturi pressure signal. Using the principles of the recently announced fluid amplifiers, weak control signals such as venturi pressure are amplified to permit proper fuel metering over a wide range of air flow rates.

As more extensively discussed in recent literature, Control Engineering of January 1963, for example, a fluid amplifier uses a relatively weak control signal to deflect a fluid jet. Because relatively large deflections in the jet are obtained with weak control signals, a more sensitive control function is obtained by utilizing the deflection of the jet rather than by directly utilizing the control signal.

This invention is illustrated as specifically applied to a fuel injection system in which fuel metering is obtained by positioning a pressure responsive spill valve to divert fuel which would otherwise flow from an engine driven pump to the injector nozzles. In the disclosed system, air flow to the engine creates a venturi pressure signal which controls the deflection of a stream of air pumped through a fluid amplifier. A stationary splitter divides the air stream into two portions, the proportions of which are determined by the venturi-pressure controlled deflection. The spill valve is responsive to the pressure differential between the two portions of the air stream and controls fuel flow to the engine to create a proper air-fuel mixture throughout the wide range of engine air flow rates.

The details as well as other objects and advantages of this invention are disclosed in the following specification and in the drawing which illustrates the above-described fuel injection system.

Referring to the drawing, an air inlet 10 is controlled by a throttle valve 12 to regulate air flow to the engine in a customary manner. A venturi 14 provides a restriction within air inlet 10 which reduces the pressure of the air flow therethrough to create a control signal related to the rate of air flow.

A fluid amplifier, indicated generally at 16, has an inlet 18 to which an air pump 20 is connected. Air pump 20 is driven either mechanically by the engine or electrically from a convenient source of electrical power.

Air flow from pump 20 through amplifier 16 is discharged from a pair of outlets 22 and 24. With the amplifier construction so far described, the proportion :of the total air flow discharged from each of outlets 22 and 24 and therefore the pressure differential between outlets 22 and 24 is determined by the location of the splitter 26.

As air flows through the inlet 10 and the venturi 14, a pressure drop is produced to create a signal which is transferred through a passage 28 to a regulating or control port 30 in the amplifier 16. This pressure signal at control port 30 deflects the air flow from pump 20 through amplifier inlet 18 to change the proportion of air discharged through each of outlets 22 and 24 and thus change the pressure differential therebetween. As air flow through the inlet 10 increases, the pressure in venturi 14 drops further; this reduced pressure sensed at control port 30 deflects a greater proportion of the air flow through amplifier 18 to outlet 22, increasing the pressure in outlet 22 and decreasing the pressure in outlet 24.

An amplifier which operates as described is known as a proportional amplifier since the proportion of fluid discharged through outlet 22 varies with the pressure at control port 30.

A fuel pump 32 delivers fuel from a tank 34 to a fuel bowl 36. The fuel in bowl 36 is maintained at a substantially constant level by a conventional float and inlet valve mechanism 38. Fuel is drawn from bowl 36 by an engine driven pump 40 and delivered through a conduit 42 to a series of injector nozzles (not shown). A bypass 44 is adapted to divert -a portion of the fuel flow from conduit 42 back to fuel bowl 36. Fuel flow through bypass 44 is controlled by a spill valve 46.

Spill valve 46 is secured to a flexible pressure responsive diaphragm 48. The position of diaphragm 48 is controlled by the pressure in chamber 50 on the upper side of the diaphragm, by the pressure in chamber 52 on the lower side of the diaphragm, and by the pressure of the fuel upon valve '46 as it flows from bypass 44."

Chambers 50 and 52 are connected through conduits 54 and 56 to amplifier outlets 22 and 24, respectively, so that the pressures in chambers 50 and 52 are controlled by the pressure of air flow through outlets 22 and 24. As air flow through inlet 10 increases and the venturi signal also increases, the reduced pressure at amplifier control port 30 diverts more of the air flow from amplifier inlet 18 through amplifier outlet 22 and less of that air flow through amplifier outlet 24. This causes an increase in pressure in outlet 22 and in chamber 50 and a decrease in pressure in outlet 24 and in chamber 52 and depresses diaphragm 48 to close spill valve 46. Less fuel is then diverted through bypass 44and more fuel is delivered to the injector nozzles through conduit 42.

Inasmuch as the pressures in chambers 50 and 52 are albove atmospheric, control linkage to provide a mechanical advantage between diaphragm 48 and spill valve 46, together with cou-nterweights and other biasing means, is made unnecessary. The sensitivity of fuel metering to a change in the air flow rate is thus increased since the frictional hysteresis of a complex mechanical linkage has been eliminated.

Those skilled in fuel injection and fluid amplifier technologies will appreciate that this invention may be used in many other arrangements for supplying fuel to an engine.

I claim:

1. An internal combustion engine fuel system comprising a fuel inlet, a valve controlling fuel flow through said inlet, a fluid amplifier including an inlet port and a pair of outlets, means to direct a flow of fluid through said amplifier from said inlet port to said outlets, said amplifier being connected to a source of regulating fluid and having means to divide the fluid flow from said inlet port between said outlets in accordance with the characteristics of said regulating fluid, and means to position said valve in accordance with the difference in the fluid flow through said outlets to thereby control fuel flow through said fuel inlet in accordance with the characteristics of said regulating fluid.

2. An internal combustion engine fuel system comprising a fuel inlet, a valve controlling fuel flow through said inlet, a fluid amplifier including an inlet port and a pair of outlets, a source of air under pressure, means to direct a flow of air from said source through said amplifier whereby an air flow path is formed between said inlet port and said outlets, sa-id amplifier further including a regulating port connected to a source of regulating fluid having a predetermined range of pressures whereby thepressure on one side of the air flow path is regulate-d to variably deflect the air flow path toward one of said outlets, said amplifier having means to divide the air flow from said inlet port between said outlets in accordance with the deflection of the air flow path, and means to position said valve in accordance with the difference in the air flow through said outlets to thereby control fuel flow through said fuel inlet in accordance with the pressure of said regulating fluid.

3. An internal combustion engine fuel injection system comprising a fuel pump having an outlet to deliver fuel under pressure to an engine, a bypass connected to said outlet to divert fuel flow from the engine, a valve controlling fuel flow through said bypass, a fluid amplifier including an inlet port and a pair of outlets, means to direct a flow of air through said amplifier from said inlet port to said outlets, said amplifier further including a regulating port connected to a source of regulating fluid and having means to divide the air flow from said inlet port between said outlets in accordance with the characteristics of said regulating fluid, and means to position said valve. in accordance with the difference in pressures in the air flow through said outlets to thereby control fuel flow to the engine.

4. An internal combustion engine fuel injection system comprising an air inlet, a venturi in said inlet to reduce the pressure of air flow therethrough, a fuel pump having an outlet to deliver fuel under pressure to the engine, a bypass connected to said outlet to divert fuel flow from the engine, a balanced valve controlling fuel flow through said bypass, fuel flow through said bypass exerting pressure on said valve in a valve-opening direction, a fluid amplifier including an inlet port and first and second outlets, a source of air under pressure, means to direct a flow of air from said source through said amplifier whereby an air flow path is formed between said inlet port and said outlets, said amplifier further including a control port connected to said venturi whereby the pressure on one side of the air flow path is reduced to deflect the air flow path toward said first outlet, said amplifier having means to divide the air flow from said inlet port between said outlets in accordance with the deflection of the air flow path, a pressure responsive diaphragm secured to aid valve, said diaphragm having first and second pressure chambers on opposing sides thereof, means connecting said first chamber and said first outlet whereby the pressure of air flow through said first outlet is exerted against said diaphragm in a valve-closing direction, and means connecting said second chamber and said second outlet References Cited by the Examiner UNITED STATES PATENTS 3,001,539 9/1961 Hurvitz 137-815 3,061,286 10/1962 Mennesson 26136 3,234,934 2/1966 Woodward 137-815 X HARRY B. THORNTON, Primary Examiner.

T. R. MILES, Assistant Examiner. 

1. AN INTERNAL COMBUSTION ENGINE FUEL SYSTEM COMPRISING A FUEL INLET, A VALVE CONTROLLING FUEL FLOW THROUGH SAID INLET, A FLUID AMPLIFIER INCLUDING AN INLET PORT AND A PAIR OF OUTLETS, MEANS TO DIRECT A FLOW OF FLUID THROUGH SAID AMPLIFIER FROM SAID INLET PORT TO SAID OUTLETS, SAID AMPLIFIER BEING CONNECTED TO A SOURCE OF REGULATING FLUID AN HAVING MEANS TO DIVIDE THE FLUID FLOW FROM SAID INLET PORT BETWEEN SAID OUTLETS IN ACCORDANCE WITH THE CHARACTERISTICS OF SAID REGULATING FLUID, AND MEANS TO POSI- 